A road intersection refers to those elements of road and transportation infrastructure where two or more roads intersect.[1] These infrastructures allow users to exchange between roads. The crossing of roads can occur with a level intersection or with an uneven intersection. It is important to note that this term can also refer to elements of other transportation systems, such as railways or bicycle paths.
Terminology
When talking about level road intersections, it is common to refer to the road section that enters the conflict zone with the term access. The conflict zone is the sum of the areas where the trajectories of the different possible movements intersect. Movements refer to the possible destinations that a vehicle can choose entering the intersection. In general there are four types of movements: right turn, direct movement, left turn and “U” movement. Very often at-grade intersections have exclusive right or left turn lanes, in order to increase the capacity of the intersection and to avoid blocking other vehicles by those who are waiting. This is known in Spain as flared because it is a widening of the regular section of the road when reaching the intersection that resembles a horn.
At-grade intersections
Controlled intersections
As intersections mean that vehicles traveling through different accesses can meet simultaneously (implying the risk of collision), at-grade intersections require some type of control so that they can operate safely. There are different intersection control codes and systems that prevent the simultaneous use of vehicles in conflicting movements. The most frequent are Stop / Stop, yield and traffic light.
Below are some signs that allow you to define the rules for operating at the intersection:
• - Give way.
• - Traffic light.
• - Stop (used in Europe).
• - Pare / Stop (used in most of South America).
• - High (used in Mexico and Central America).
• - Roundabout or roundabout (used in most of Europe).
Safe intersections
Introduction
A road intersection refers to those elements of road and transportation infrastructure where two or more roads intersect.[1] These infrastructures allow users to exchange between roads. The crossing of roads can occur with a level intersection or with an uneven intersection. It is important to note that this term can also refer to elements of other transportation systems, such as railways or bicycle paths.
Terminology
When talking about level road intersections, it is common to refer to the road section that enters the conflict zone with the term access. The conflict zone is the sum of the areas where the trajectories of the different possible movements intersect. Movements refer to the possible destinations that a vehicle can choose entering the intersection. In general there are four types of movements: right turn, direct movement, left turn and “U” movement. Very often at-grade intersections have exclusive right or left turn lanes, in order to increase the capacity of the intersection and to avoid blocking other vehicles by those who are waiting. This is known in Spain as flared because it is a widening of the regular section of the road when reaching the intersection that resembles a horn.
At-grade intersections
Controlled intersections
As intersections mean that vehicles traveling through different accesses can meet simultaneously (implying the risk of collision), at-grade intersections require some type of control so that they can operate safely. There are different intersection control codes and systems that prevent the simultaneous use of vehicles in conflicting movements. The most frequent are Stop / Stop, yield and traffic light.
Below are some signs that allow you to define the rules for operating at the intersection:
• - Give way.
• - Roundabout or roundabout (used in most of North America).
• - Priority road.
• - Priority road (Mexico).
• - Level intersection with priority.
• - Level intersection with right priority.
• - Another level crossing proximity sign (used especially in Mexico).
Within the level intersections, there is also the roundabout or roundabout. Unlike the previous ones, it works in a circular movement in which the vehicles inside the roundabout have priority, so technically and under normal conditions all the roads or tracks that reach the roundabout have the same preference.
Uncontrolled intersections
There are intersections that do not have any type of control. For these intersections there are some rules: Give priority to the first vehicle that arrives, to the vehicle that arrives from the right (in countries where drivers go from the left the rule can be reversed, giving way to vehicles that come from the left) or to the vehicle that travels on a paved road (when traveling on an unpaved road), these rules may change according to the country or region. These intersections are found exclusively in rural areas or residential and industrial areas with very low traffic.
Uneven intersections (interchanges)
Within the range of intersections, intersections at different levels are those with the greatest capacity. They are called links or exchangers. They are based on the idea of segregating conflicting currents at different levels through tunnels or viaducts. The different levels at the intersection are interconnected by ramps. These connections allow exchanges of paths. These types of solutions are used on expressways (where traffic lights cannot be placed) and at intersections that cannot provide a good service at the level. Its implementation must be carefully evaluated in necessary cases due to the large investments required.
There are dozens of possible standard grade intersections. Among the most frequent is the clover with its different variations. Clovers are used when the flow on both roads is high, for example the intersection of two highways where all turns (right, direct, left and U) through all accesses are allowed. Similarly, there are mill and turbine intersections, but the latter are intersections of 3 or more levels, while cloverleaf only requires raising one of the two conflicting paths.
• - Clover.
• - Clover with return paths.
• - Diamond.
• - Modified diamond.
• - Windmill.
• - Uneven roundabout.
• - Another type of uneven roundabout.
• - Turbine.
• - Maltese.
• - Spaghetti.
Engineering concepts
Contenido
Las intersecciones viales son de especial interés dentro del estudio de la ingeniería de tránsito, por ser los puntos que generan mayores retrasos dentro de la red.[2][3].
Intersection Evaluation
Intersections are evaluated according to the quality of service they are presenting at different times of the day. There are standardized procedures to determine the level of service that the infrastructure is presenting. While for discontinuous flow roads, the speed allows determining the level of service, at intersections it is the delays (measured in minutes per access) or the length of the different lines or queues (at each access).
Intersection Type Selection
The type of intersection and control at the intersection are decided in a complex process. The most frequent reason is traffic that is useful in the present and will serve in the future. For low traffic volumes, priority intersections (with stop, yield) are sufficient. When the flow on the main road is medium, it becomes difficult for vehicles on the roads that cross it to find a space between cars to cross or merge. This leads to the need to change control. Usually a traffic light is used, but also, depending on the geometry and traffic conditions, a roundabout is installed. When these controls cannot provide good service at the intersection (long lines and substantial delays), it is recommended to build intersections at different levels.
[2] ↑ Sheffi (1984) "Urban Transport Networks". Prentice Hall, Nueva Jersey, EE.UU.
[3] ↑ William Castro García (n.d.) INDICADORES DE OPERACIÓN DE INTERSECCIONES A NIVEL CALIBRADAS.
• - Traffic light.
• - Stop (used in Europe).
• - Pare / Stop (used in most of South America).
• - High (used in Mexico and Central America).
• - Roundabout or roundabout (used in most of Europe).
• - Roundabout or roundabout (used in most of North America).
• - Priority road.
• - Priority road (Mexico).
• - Level intersection with priority.
• - Level intersection with right priority.
• - Another level crossing proximity sign (used especially in Mexico).
Within the level intersections, there is also the roundabout or roundabout. Unlike the previous ones, it works in a circular movement in which the vehicles inside the roundabout have priority, so technically and under normal conditions all the roads or tracks that reach the roundabout have the same preference.
Uncontrolled intersections
There are intersections that do not have any type of control. For these intersections there are some rules: Give priority to the first vehicle that arrives, to the vehicle that arrives from the right (in countries where drivers go from the left the rule can be reversed, giving way to vehicles that come from the left) or to the vehicle that travels on a paved road (when traveling on an unpaved road), these rules may change according to the country or region. These intersections are found exclusively in rural areas or residential and industrial areas with very low traffic.
Uneven intersections (interchanges)
Within the range of intersections, intersections at different levels are those with the greatest capacity. They are called links or exchangers. They are based on the idea of segregating conflicting currents at different levels through tunnels or viaducts. The different levels at the intersection are interconnected by ramps. These connections allow exchanges of paths. These types of solutions are used on expressways (where traffic lights cannot be placed) and at intersections that cannot provide a good service at the level. Its implementation must be carefully evaluated in necessary cases due to the large investments required.
There are dozens of possible standard grade intersections. Among the most frequent is the clover with its different variations. Clovers are used when the flow on both roads is high, for example the intersection of two highways where all turns (right, direct, left and U) through all accesses are allowed. Similarly, there are mill and turbine intersections, but the latter are intersections of 3 or more levels, while cloverleaf only requires raising one of the two conflicting paths.
• - Clover.
• - Clover with return paths.
• - Diamond.
• - Modified diamond.
• - Windmill.
• - Uneven roundabout.
• - Another type of uneven roundabout.
• - Turbine.
• - Maltese.
• - Spaghetti.
Engineering concepts
Contenido
Las intersecciones viales son de especial interés dentro del estudio de la ingeniería de tránsito, por ser los puntos que generan mayores retrasos dentro de la red.[2][3].
Intersection Evaluation
Intersections are evaluated according to the quality of service they are presenting at different times of the day. There are standardized procedures to determine the level of service that the infrastructure is presenting. While for discontinuous flow roads, the speed allows determining the level of service, at intersections it is the delays (measured in minutes per access) or the length of the different lines or queues (at each access).
Intersection Type Selection
The type of intersection and control at the intersection are decided in a complex process. The most frequent reason is traffic that is useful in the present and will serve in the future. For low traffic volumes, priority intersections (with stop, yield) are sufficient. When the flow on the main road is medium, it becomes difficult for vehicles on the roads that cross it to find a space between cars to cross or merge. This leads to the need to change control. Usually a traffic light is used, but also, depending on the geometry and traffic conditions, a roundabout is installed. When these controls cannot provide good service at the intersection (long lines and substantial delays), it is recommended to build intersections at different levels.